Pump monitoring device, vacuum processing device, and vacuum pump

ABSTRACT

Provided is a pump monitoring device for detecting abnormalities of multiple vacuum pumps connected to the same chamber, the pump monitoring device being configured to estimate occurrence of the abnormality at any of the multiple vacuum pumps based on a comparison result of signals indicating rotation states of pump rotors of the multiple vacuum pumps.

TECHNICAL FIELD

The present invention relates to a pump monitoring device, a vacuum processing device, and a vacuum pump.

BACKGROUND ART

At a step such as dry etching or CVD in manufacturing of a semiconductor or a liquid crystal panel, processing is performed in a high-vacuum process chamber, and therefore, e.g., a vacuum pump such as a turbo-molecular pump is used as the technique of discharging gas from the process chamber to maintain a high vacuum state. In the case of discharging the gas from the process chamber in, e.g., dry etching or CVD, a reactive product is accumulated in the pump due to gas discharge.

Regarding such reactive product accumulation, PTL1 discloses the method for sensing a product accumulated in a pump. In the accumulated product sensing method disclosed in PTL1, a current value of a motor configured to rotatably drive a rotary body of the pump is measured, and in a case where the amount of change in the measurement value with respect to a motor current initial value is equal to or greater than a predetermined value, a warning is issued.

CITATION LIST Patent Literature

PTL1: Japanese Patent No. 5767632

SUMMARY OF THE INVENTION Technical Problem

However, the flow rate of gas to be discharged actually greatly fluctuates in a single process, and therefore, the current value of the motor configured to rotatably drive the rotary body also greatly fluctuates in association with fluctuation in the gas flow rate.

For this reason, there are problems that the warning is also issued even in a case where the motor current value fluctuates due to fluctuation in the gas flow rate and erroneous determination cannot be avoided.

Solution To Problem

According to a first aspect of the present invention, a pump monitoring device is a pump monitoring device for detecting abnormalities of multiple vacuum pumps connected to the same chamber, the pump monitoring device being configured to estimate occurrence of the abnormality at any of the multiple vacuum pumps based on a comparison result of signals indicating rotation states of pump rotors of the multiple vacuum pumps.

A second aspect of the present invention is the pump monitoring device of the first aspect, in which each signal indicating the rotation state is a motor current value of a motor configured to rotatably drive the pump rotor and based on a difference between the different motor current values of the vacuum pumps, it is estimated that the abnormality has been caused at any of the multiple vacuum pumps.

A third aspect of the present invention is the pump monitoring device of the first aspect, in which each pump rotor is magnetically levitated and supported by a magnetic bearing and each signal indicating the rotation state is calculated based on a magnetic bearing control amount of the magnetic bearing.

A fourth aspect of the present invention is the pump monitoring device of the first aspect, which further includes an input section configured to receive, from one or more vacuum processing devices including multiple vacuum pumps configured to perform vacuum pumping for chambers, signals indicating rotation states of the multiple vacuum pumps. For each vacuum processing device, it is estimated that an abnormality has been caused at any of the multiple vacuum pumps.

According to a fifth aspect of the present invention, a vacuum processing device includes a chamber, multiple vacuum pumps configured to perform vacuum pumping for the chamber, and the pump monitoring device of the first aspect.

According to a sixth aspect of the present invention, a vacuum pump including the pump monitoring device of the first aspect, a pump rotor to be rotatably driven by a motor, and an input section configured to receive signals indicating rotation states from other vacuum pumps. The pump monitoring device compares a signal indicating a rotation state of the pump rotor and the signals input through the input section and indicating the rotation states to estimate a pump abnormality.

Advantageous Effects of Invention

According to the present invention, erroneous determination upon abnormality detection of the vacuum pump can be prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view of a semiconductor manufacturing device in a first embodiment;

FIG. 2 is a sectional view of details of a pump main body;

FIG. 3 is a graph of one example of a motor current measurement value;

FIG. 4 is a block diagram of vacuum pumps and a pump monitoring device;

FIG. 5 is a view of a configuration of a displacement sensor;

FIG. 6 is a flowchart of one example of abnormality determination processing;

FIG. 7 is a block diagram for describing magnetic bearing control;

FIG. 8 is a graph of one example of an XY value;

FIG. 9 is a flowchart of one example of abnormality determination processing in a second embodiment;

FIG. 10 is a diagram for describing a third embodiment; and

FIG. 11 is a diagram for describing a fourth embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment

FIG. 1 is a view of a semiconductor manufacturing device 10 in a first embodiment. The semiconductor manufacturing device 10 is a vacuum processing device such as an etching device. In an example illustrated in FIG. 1, two vacuum pumps 1A, 1B are attached to a process chamber 100, but the present invention is also similarly applicable to a case where three or more vacuum pumps are attached.

The vacuum pump 1A is attached to the process chamber 100 through a valve 3A, and the vacuum pump 1B is attached to the process chamber 100 through a valve 3B. The semiconductor manufacturing device 10 includes a main control device 110 configured to control the entirety of the manufacturing device including the vacuum pumps 1A, 1B and the valves 3A, 3B. The main control device 110 includes a monitoring device 4 configured to monitor whether or not the vacuum pumps 1A, 1B have abnormalities. The vacuum pumps 1A, 1B are the same type of vacuum pump, and each include pump main bodies 11 and controllers 12 configured to drivably control the pump main bodies 11. Each controller 12 of the vacuum pumps 1A, 1B is connected to the main control device 110 of the semiconductor manufacturing device 10 through a communication line 40.

FIG. 2 is a sectional view of details of the pump main body 11. The vacuum pumps 1A, 1B in the present embodiment are magnetic bearing turbo-molecular pumps, and a rotary body R is provided at the pump main body 11. The rotary body R includes a pump rotor 14 and a rotor shaft 15 fastened to the pump rotor 14.

The pump rotor 14 is provided with multiple stages of rotor blades 14 a on an upstream side, and is provided with a cylindrical portion 14 b forming a screw groove pump on a downstream side. Accordingly, a stationary side is provided with multiple stationary blade stators 62 and a cylindrical screw stator 64. In an example illustrated in FIG. 2, a screw groove is formed on a screw stator 64 side, but may be formed at the cylindrical portion 14 b. Each stationary blade stator 62 is mounted on a base 60 through a spacer ring 63.

The rotor shaft 15 is magnetically levitated and supported by radial magnetic bearings 17A, 17B and an axial magnetic bearing 17C provided at the base 60, and is rotatably driven by a motor 16. Each of the magnetic bearings 17A to 17C includes electromagnets and displacement sensors, and the levitation position of the rotor shaft 15 is detected by the displacement sensors. The number of rotations of the rotor shaft 15 is detected by a rotation number sensor 18. In a case where the magnetic bearings 17A to 17C are not in operation, the rotor shaft 15 is supported by emergency mechanical bearings 66 a, 66 b.

A pump case 61 provided with a suction opening 61 a is bolted to the base 60. An exhaust port 65 is provided at an exhaust opening 60 a of the base 60, and a back pump is connected to the exhaust port 65. When the rotor shaft 15 fastened to the pump rotor 14 is rotated at high speed by the motor 16, gas molecules on a suction opening 61 a side are discharged to an exhaust port 65 side.

A heater 19 and a refrigerant pipe 20 in which refrigerant such as coolant water flows are provided at the base 60. In the case of discharging gas easily leading to accumulation of a reactive product, ON/OFF of the heater 19 and ON/OFF of the refrigerant flowing in the refrigerant pipe 20 are, for reducing product accumulation on a screw groove pump portion and the rotor blades 14 a on the downstream side, performed to perform such temperature adjustment that a base temperature in the vicinity of a screw stator fixing portion reaches a predetermined temperature, for example. Note that although not shown in the figure, an electromagnetic valve configured to turn on/off the refrigerant is provided at the refrigerant pipe 20.

It can be assumed that two vacuum pumps 1A, 1B attached to the same process chamber 100 are under the substantially same use conditions. Moreover, pump maintenance due to accumulation of the reactive product is also performed at the same timing. For these reasons, it is assumed that a reactive product accumulation state over use time is the substantially same between the vacuum pump 1A and the vacuum pump 1B.

FIG. 3 is a graph of one example of motor current measurement values of the vacuum pump 1A and the vacuum pump 1B, and illustrates the measurement values in a state in which accumulation of the reactive product has been progressed. In FIG. 3, the horizontal axis represents time, and the vertical axis represents a motor current value. A line MA indicated by a solid line indicates the motor current value of the vacuum pump 1A, and a line MB indicated by a dashed line indicates the motor current value of the vacuum pump 1B. In a period indicated by a reference character B, gas introduction into the process chamber 100 is performed, and the motor current values MA, MB increase.

In an operation state in which introduction and stoppage of gas are repeated as in FIG. 3, the motor current value greatly fluctuates in association with fluctuation in a gas flow rate. However, the vacuum pumps 1A, 1B are the same type of vacuum pump, and are under the substantially same use conditions. Thus, as illustrated in FIG. 3, the motor current values MA, MB show a substantially similar change trend regardless of a change in a gas introduction amount, and a difference between the motor current values MA, MB is small.

However, in a state in which a reactive product accumulation amount has increased, an instantaneous increase in the motor current value as indicated by a reference character A of FIG. 3 is shown. This might be because when accumulation of the reactive product progresses, a gap between the cylindrical portion 14 b and the screw stator 64 as illustrated in FIG. 2 decreases due to the accumulated product, the cylindrical portion 14 b and the screw stator 64 incidentally contact each other in the case of swinging the pump rotor 14, and an instantaneous increase in the motor current value is caused. In the example illustrated in FIG. 3, the motor current value MA of the vacuum pump 1A shows an instantaneous increase. It has been found that such a phenomenon is caused when the reactive product accumulation amount becomes excessive and a failure (e.g., unavailability in pump start-up due to contact between the cylindrical portion 14 b and the screw stator 64) due to the accumulated product is caused within about several days to two weeks after an instantaneous increase in the motor current value has been caused.

For this reason, in the present embodiment, the difference between the motor current value MA of the vacuum pump 1A and the motor current value MB of the vacuum pump 1B is calculated, and in a case where the magnitude of such a difference exceeds a preset threshold (e.g., in the case of the situation indicated by the reference character A of FIG. 3), a warning to a user is issued.

FIG. 4 is a block diagram of configurations of the vacuum pumps 1A, 1B provided at the semiconductor manufacturing device 10. The vacuum pumps 1A, 1B are the same type of vacuum pump, the pump main body 11 including the motor 16, a magnetic bearing 17, and the rotation number sensor 18 and the controller 12 including a communication port 21, a magnetic bearing control section 22, a motor control section 23, and a storage section 24. Note that in FIG. 4, the radial magnetic bearings 17A, 17B and the axial magnetic bearing 17C of FIG. 2 are collectively described as the magnetic bearing 17. Moreover, the main control device 110 includes a pump monitoring device 120, a display section 130, and a communication port 44.

The motor control section 23 estimates the number of rotations of the rotor shaft 15 based on a rotation signal detected by the rotation number sensor 18, thereby controlling the motor 16 to a predetermined target rotation number based on the estimated number of rotations. Note that a load on the pump rotor 14 increases as the gas flow rate increases, and therefore, a motor current is controlled according to the load to maintain the predetermined target rotation number. The magnetic bearing 17 includes the bearing electromagnets and the displacement sensors configured to detect the levitation position of the rotor shaft 15.

FIG. 5 is a view of a configuration of the displacement sensor. The radial magnetic bearing 17A of FIG. 2 includes magnetic bearings for two axes of an x-axis and a y-axis, and includes a pair of displacement sensors X1 a, X1 b for the x-axis and a pair of displacement sensors Y1 a, Y1 b for the y-axis. Similarly, the radial magnetic bearing 17B of FIG. 2 includes magnetic bearings for two axes of the x-axis and the y-axis, and includes a pair of displacement sensors X2 a, X2 b for the x-axis and a pair of displacement sensors Y2 a, Y2 b for the y-axis. Moreover, the axial magnetic bearing 17C includes a displacement sensor z configured to detect the displacement of the rotor shaft 15 in an axial direction thereof.

Returning to FIG. 4, detection signals are input from the displacement sensors X1 a, X1 b, Y1 a, Y1 b, X2 a, X2 b, Y2 a, Y2 b, z provided at the pump main body 11 of the vacuum pump 1A to the magnetic bearing control section 22 provided at the controller 12 of the vacuum pump 1A. Similarly, detection signals are input from the displacement sensors X1 a, X1 b, Y1 a, Y1 b, X2 a, X2 b, Y2 a, Y2 b, z provided at the pump main body 11 of the vacuum pump 1B to the magnetic bearing control section 22 provided at the controller 12 of the vacuum pump 1B.

The magnetic bearing control section 22 of the controller 12 controls, based on the detection signals of the displacement sensors X1 a, X1 b, Y1 a, Y1 b, X2 a, X2 b, Y2 a, Y2 b, z, the excitation current of the magnetic bearing 17 such that the rotor shaft 15 is magnetically supported at a target levitation position. In the storage section 24 of the controller 12, a parameter necessary for motor control and magnetic bearing control is stored, and data on the type of the vacuum pump 1A, 1B is stored.

As described above, the pump monitoring device 120 provided at the main control device 110 is a device configured to monitor whether or not the abnormality (i.e., excessive reactive product accumulation) has been caused at the vacuum pumps 1A, 1B attached to the process chamber 100. The controllers 12 of the vacuum pumps 1A, 1B and the main control device 110 exchange information via communication. An example illustrated in FIG. 4 shows a case where a signal is exchanged via serial communication. The communication port 21 is provided at the controller 12, and the communication port 44 is also provided at the main control device 110. The communication port 21 of the controller 12 is connected to the communication port 44 of the main control device 110 through the communication line 40.

Description of Monitoring Method

The pump monitoring device 120 uses, as information for detecting the abnormalities of the vacuum pumps 1A, 1B, a signal indicating a rotation state of each pump rotor 14. In the present embodiment, a case where the motor current values MA, MB of the vacuum pumps 1A, 1B are used as the signals indicating the rotation states of the pump rotors 14 will be described.

In the motor control section 23 of the controller 12, the rotation speed of the motor 16 is calculated based on a detection value of the rotation number sensor 18, and performs feedback control such that the detected rotation speed reaches a target rotation speed. In a state in which a series of processes is performed as in FIG. 3, the motor control section 23 performs the steady-state operation control of maintaining the rotation speed at a rated rotation speed. As described above, gas introduction into the process chamber 100 is performed in an interval indicated by the reference character B, and therefore, the load on the pump rotor 14 increases. The motor control section 23 performs the control of maintaining the motor rotation speed at the rated rotation speed, and therefore, the motor current value MA, MB increases in association with an increase in the gas load.

The motor current values MA, MB of the vacuum pumps 1A, 1B acquired through the communication lines 40 are input to the pump monitoring device 120. The pump monitoring device 120 calculates the difference ΔM (=MA−MB) between the motor current values MA, MB. The pump monitoring device 120 determines as abnormal in a case where the magnitude |ΔM| of the difference AM exceeds a predetermined threshold α. For example, at a time point t1 of FIG. 3, the difference AM between the motor current values MA, MB satisfies |ΔM|<α, and therefore, it is not determined as abnormal. However, at a time point t2, |ΔM|>α is satisfied, and therefore, it is determined as abnormal.

The vacuum pumps 1A, 1B are under the substantially same use environment, and are in the substantially same reactive product accumulation situation. When the reactive product accumulation amount becomes excessive, an instantaneous increase in the motor current value is caused, the instantaneous increase being assumed as resulting from incidental contact between the cylindrical portion 14 b and the screw stator 64. However, such an increase in the motor current value is incidentally caused, and it is not clear whether such an increase is caused at the vacuum pump 1A or the vacuum pump 1B. In the present embodiment, the magnitude |ΔM| of the difference ΔM is compared with the threshold α, and therefore, even in a case where the abnormality (i.e., an increase in the motor current value) is caused at any of the vacuum pumps 1A, 1B, such an abnormality can be detected.

Regarding the threshold α, a preset value may be used, or the threshold α may be set based on the motor current values MA, MB of the actually-operated vacuum pumps 1A, 1B. In the case of setting the threshold α based on the motor current values MA, MB in an operating state, the threshold α may be set based on the motor current values MA, MB in an initial state with a short use period after the start of use of the vacuum pumps 1A, 1B, or may be set based on the motor current values MA, MB until determination of the abnormality after the point of time of starting the use.

In the initial state, the product accumulation amount is small, and therefore, the threshold α can be set without influence of product accumulation. Moreover, in the initial state, almost no instantaneous increase in the motor current value as indicated by the reference character A of FIG. 3 is caused. The pump monitoring device 120 acquires many pieces of data on the motor current values MA, MB over time, and based on such data, calculates the standard deviation σ of the difference ΔM. |ΔM| in an abnormal state is significantly greater than |ΔM| in a normal state, and in terms of avoidance of erroneous detection, e.g., a great value of 6 σ is set as the threshold for the standard deviation σ.

FIG. 6 is a flowchart of one example of abnormality determination processing by the pump monitoring device 120. At a step S100, the threshold α based on the motor current values MA, MB in the initial state is set. Specifically, after the vacuum pumps 1A, 1B have been attached to the process chamber 100, the motor current values MA, MB are sampled at certain time intervals in the initial state until a lapse of a predetermined period after the start of pump operation. In this case, sampling of the motor current values MA, MB is performed at the same timing. The difference ΔM=MA−MB is obtained for the obtained multiple pairs of motor current values MA, MB, and the standard deviation a of the difference ΔM is calculated. Then, 6 σ is set as the threshold α. The threshold α=6 σ is stored in a storage section (not shown) provided at the pump monitoring device 120 of FIG. 4.

Subsequently, at a step S110, the motor current values MA, MB are read, and at a subsequent step S120, the magnitude |ΔM| of the difference ΔM is calculated. At a step S130, it is determined whether or not a magnitude relationship between |ΔM| and the threshold α satisfies |ΔM|>α. When it is, at the step S130, determined as |ΔM|>α, the processing proceeds to a step S140 to execute warning processing. For example, the warning is displayed on the display section 130 of the main control device 110, and in this manner, the user is notified of the necessity of maintenance of the vacuum pumps 1A, 1B attached to the process chamber 100.

On the other hand, in a case where it is, at the step S130, determined as |ΔM|≤α, the processing returns to the step S110 to re-execute the processing from the step S110 to the step S130. The processing from the step S110 to the step S130 is repeatedly executed at predetermined time intervals until it is determined as yes at the step S130.

(C1) As described above, the pump monitoring device 120 configured to detect the abnormalities of the multiple vacuum pumps 1A, 1B connected to the same process chamber 100 estimates, based on a comparison result of the signal indicating the rotation state of each pump rotor 14 of the multiple vacuum pumps 1A, 1B, that the abnormality has been caused at any of the vacuum pumps 1A, 1B.

The vacuum pumps 1A, 1B are connected to the same process chamber 100. Thus, the vacuum pumps 1A, 1B are in the substantially same pump state such as the reactive product accumulation amount, and even in a case where the motor current values fluctuate due to fluctuation in the gas flow rate, the signals indicating the rotation states of the pump rotors 14 show a similar trend. Thus, in a case where comparison of the signals indicating the rotation states shows that the signals (in the example of FIG. 3, the motor current values MA, MB) indicating the rotation states deviate from each other as in the time point t2 of FIG. 3, it can be easily estimated that the abnormality has been caused at any of the vacuum pumps 1A, 1B, and erroneous determination as in a typical case can be prevented.

(C2) For example, the motor current values MA, MB of the motors 16 configured to rotatably drive the pump rotors 14 can be used as the signals indicating the above-described rotation states. In this case, based on the difference between the different motor current values MA, MB of the vacuum pumps 1A, 1B, the magnitude |ΔM| of the difference ΔM between the motor current values MA, MB is, for example, compared with the threshold α to estimate that the abnormality has been caused at any of the vacuum pumps 1A, 1B.

(C5) Moreover, as illustrated in FIG. 1, the semiconductor manufacturing device 10 as the vacuum processing device including the process chamber 100 and the multiple vacuum pumps 1A, 1B configured to perform vacuum pumping for the process chamber 100 may include the above-described pump monitoring device 120. By the warning from the pump monitoring device 120, an operator can properly recognize the timing of maintenance of the vacuum pumps 1A, 1B attached to the process chamber 100.

Note that in the above-described embodiment, in the case of setting the threshold a upon determination on whether or not the abnormality has been caused, e.g., α=6 σ is set using the standard deviation a of the difference=MA−MB, but the average of the difference may be used for setting.

In the above-described embodiment, the case where two vacuum pumps are attached to the process chamber 100 has been described by way of example, but the present invention is also applicable to a case where three or more vacuum pumps are attached. In a case where three or more vacuum pumps are attached, these vacuum pumps are used under the same conditions, and therefore, in a case where the abnormality (i.e., excessive reactive product accumulation) has been detected at any one of the multiple vacuum pumps, the pump monitoring device 120 issues such a warning that maintenance needs to be performed for all of the multiple vacuum pumps attached to the process chamber 100.

The pump monitoring device 120 acquires the motor current values from any two of the multiple vacuum pumps attached to the process chamber 100, and determines whether or not the magnitude |ΔM| of the difference between these two motor current values satisfies |ΔM|>α. Such determination for any two of the multiple vacuum pumps is performed for all of the multiple vacuum pumps. For example, in a case where five vacuum pumps 1A, 1B, 1C, 1D, 1E are attached to the process chamber 100, it is, for three types of combinations of (1A, 1B), (1C, 1D), (1E, 1A), determined whether or not |ΔM|>α is satisfied. Then, in a case where at least one of three types of combinations satisfies |ΔM|>α, maintenance for all of five vacuum pumps 1A, 1B, 1C, 1D, 1E is warned.

Note that three types of combinations (1A, 1B), (1C, 1D), (1E, 1A) include all of the vacuum pumps 1A, 1B, 1C, 1D, 1E attached to the process chamber 100, and therefore, abnormality determination is performed for all of the vacuum pumps 1A to 1E in such a manner that the above-described abnormality detection processing is performed for three types of combinations.

Second Embodiment

In the above-described first embodiment, the motor current values MA, MB are used as the signals indicating the rotation states of the pump rotors 14. However, in a second embodiment, a signal indicating a rotation state is calculated based on a magnetic bearing control amount generated based on a displacement signal of a displacement sensor. As illustrated in FIG. 5, the displacement sensors configured to detect the levitation position of a rotor shaft 15 are provided at the magnetic bearings 17A, 17B, 17C. Hereinafter, a case where displacement signals of displacement sensors X2 a, X2 b, Y2 a, Y2 b configured to detect the levitation position in a radial direction are used as the signals indicating the rotation state will be described.

As illustrated in FIG. 5, the radial magnetic bearing 17A includes two pairs of electromagnets arranged to sandwich the rotor shaft 15. The pair of displacement sensors X2 a, X2 b is provided for one pair of electromagnets arranged in an x-axis direction, and the pair of displacement sensors Y2 a, Y2 b is provided for the other pair of electromagnets arranged in a y-axis direction.

FIG. 7 is a block diagram for describing magnetic bearing control for the displacement sensors X2 a, X2 b. A block diagram for the displacement sensors Y2 a, Y2 b is totally similar to the case of FIG. 7. Displacement signals of the displacement sensors X2 a, X2 b change according to the size of a gap between the displacement sensor X2 a, X2 b and the rotor shaft 15. The displacement signals from the displacement sensors X2 a, X2 b are input to a difference amplifier 602. A difference signal Vdif as a difference value between these signals is output from the difference amplifier 602.

The difference signal Vdif is input to a PID control circuit 53. The PID control circuit 53 performs PID arithmetic processing for a current value to be applied to an electromagnet 37 x such that the difference signal Vdif reaches zero, i.e., the rotor shaft 15 is supported at the center between the displacement sensors X2 a, X2 b, and outputs the resultant value as the magnetic bearing control amount to a current amplifier 55. The current amplifier 55 supplies an electromagnet current corresponding to the input magnetic bearing control amount to the electromagnet 37 x.

In the present embodiment, an XY value as the signal indicating the rotation state of a pump rotor 14 is calculated based on the magnetic bearing control amount output from the PID control circuit 53 to the current amplifier 55. Hereinafter, the magnetic bearing control amount in the x-axis direction is indicated as PID-IX, and the magnetic bearing control amount in the y-axis direction is indicated as PID-IY. The pump monitoring device 120 reads these magnetic bearing control amounts PID-IX, PID-IY from each of vacuum pumps 1A, 1B, thereby calculating the XY value represented by Expression (1):

XY={(PID−IX)²+(PID−IY)²}^(1/2)  (1)

The XY value represented by Expression (1) is introduced as an indicator of horizontal force on the pump rotor 14, i.e., the deviation of the center of the pump rotor 14 with respect to a target levitation position. A greater horizontal force, i.e., a greater deviation of the center of the pump rotor 14 with respect to the target levitation position, results in a greater XY value. When a cylindrical portion 14 b and a screw stator 64 contact each other due to an increase in a reactive product accumulation amount and force is applied to the pump rotor 14, the deviation of the center as the rotation state of the pump rotor 14 increases, and the XY value also increases.

FIG. 8 is a graph of one example of the XY value. FIG. 8 illustrates the XY values detected at two vacuum pumps 1A, 1B attached to the same process chamber, and a pump state is in a state at the substantially same moment as that of the case illustrated in FIG. 3. In FIG. 8, the vertical axis indicates the XY value, the horizontal axis indicates time, a line SA indicated by a solid line indicates the XY value of the vacuum pump 1A, and a line SB indicated by a dashed line indicates the XY value of the vacuum pump 1B.

The pattern of change in each of the XY values SA, SB in an interval C is similar in any interval C. However, the magnitude |ΔXY| of a difference between the XY value SA and the XY value SB at a time point t3 is greater than |ΔXY| at other time points. It is assumed that such an instantaneous increase in |ΔXY| results from contact between the cylindrical portion 14 b and the screw stator 64. Actually, in a case where an instantaneous increase in the motor current value as indicated by the reference character A of FIG. 3 is caused, an instantaneous increase in |ΔXY| as illustrated in FIG. 8 is also caused.

Note that in a case where disturbance acts on the pump rotor 14 or a gas load rapidly changes, the pump rotor 14 also swings, and therefore, the magnetic bearing control amounts PID-IX, PID-IY fluctuate to reduce such swing. For this reason, even in a state without contact between the cylindrical portion 14 b and the screw stator 64, the XY value fluctuates to a certain extent.

In the present embodiment, the pump monitoring device 120 calculates each of the XY values of the vacuum pumps 1A, 1B. Then, in a case where the magnitude |ΔXY| of the difference ΔXY between two calculated XY values becomes greater than a predetermined threshold, the pump monitoring device 120 issues such a warning that an abnormality (i.e., excessive reactive product accumulation) has been caused at any of the vacuum pumps 1A, 1B. That is, the necessity of maintenance of the vacuum pumps 1A, 1B is warned. Note that the method for setting a threshold α may be similar to that in the case of the first embodiment, and 6 σ may be taken as the threshold α in a case where the standard deviation of the difference ΔXY is σ, for example.

FIG. 9 is a flowchart of one example of abnormality determination processing in the second embodiment. At a step S200, the threshold α based on the XY values SA, SB in an initial state is set as in the case of the first embodiment. Processing similar to the step S100 of FIG. 6 may be performed with the motor current values MA, MB in the case of the first embodiment being replaced with the XY values SA, SB, and detailed description thereof will be omitted. The calculated threshold α is stored in a storage section (not shown) provided at the pump monitoring device 120.

Subsequently, at a step S210, the XY values SA, SB are read. At a step S220, the magnitude |ΔXY|=|SA−SB| of the difference between the XY values is calculated. At a step S230, it is determined whether or not a magnitude relationship between |ΔXY| and the threshold α satisfies |ΔXY|>α. At the step S230, when it is determined as |ΔXY|>α, the processing proceeds to a step S240 to execute warning processing similar to the warning processing at the step S140 of the first embodiment.

On the other hand, in a case where it is, at the step S230, determined as |ΔXY|≤α, the processing returns to the step S210 to re-execute the processing from the step S210 to the step S230. The processing from the step S210 to the step S230 is repeatedly executed at predetermined time intervals until it is determined as yes at the step S230.

(C3) As described above, in the second embodiment, the XY value as the signal indicating the rotation state is calculated based on the magnetic bearing control amounts PID-IX, PID-IY when the pump rotor 14 is magnetically levitated and supported by the magnetic bearings. Then, for the vacuum pumps 1A, 1B, the XY values SA, SB are calculated. The magnitude |ΔXY| of the difference between these values is compared with the threshold α, and in this manner, it is estimated that the abnormality has been caused at any of the vacuum pumps 1A, 1B.

The XY value indicates the deviation of the center of the pump rotor 14 with respect to the target levitation position. When the cylindrical portion 14 b and the screw stator 64 contact each other due to an increase in the reactive product accumulation amount and the force is applied to the pump rotor 14, the deviation of the center as the rotation state of the pump rotor 14 increases, and the XY value also increases. Thus, for the vacuum pumps 1A, 1B, the magnitude |ΔXY| of the difference between the XY values is compared with the threshold α, and in this manner, the abnormality (i.e., excessive reactive product accumulation) can be easily detected at any of the vacuum pumps 1A, 1B.

Note that detection on occurrence of the abnormality at any of the vacuum pumps 1A, 1B may be made using both of the difference ΔXY between the XY values and the above-described difference AM between the motor current values.

In description above, in the case of detecting contact between the pump rotor 14 and the screw stator 64, the displacement signals of the displacement sensors X2 a, X2 b, Y2 a, Y2 b close to the pump rotor 14 in an axial direction are used, but displacement signals of displacement sensors X1 a, X1 b, Y1 a, Y1 b may be used.

Third Embodiment

FIG. 10 is a diagram for describing a third embodiment, and is a block diagram of configurations of vacuum pumps 1A, 1B provided at a semiconductor manufacturing device 10 as in FIG. 4. In the above-described first and second embodiments, the pump monitoring device 120 is provided at the main control device 110 of the semiconductor manufacturing device 10. On the other hand, in a third embodiment, pump monitoring devices 120 are each provided in controllers 12 of the vacuum pumps 1A, 1B. Other configurations are similar to those illustrated in FIG. 4.

The pump monitoring device 120 provided in the controller 12 of the vacuum pump 1A acquires a signal indicating a rotation state of a pump rotor 14 of the vacuum pump 1A, and through a communication line 40, acquires a signal indicating a rotation state of a pump rotor 14 of the other vacuum pump 1B from the vacuum pump 1B. Similarly, the pump monitoring device 120 provided in the controller 12 of the vacuum pump 1B acquires the signal indicating the rotation state of the pump rotor 14 of the vacuum pump 1B, and through the communication line 40, acquires the signal indicating the rotation state of the pump rotor 14 of the other vacuum pump 1A from the vacuum pump 1A.

Motor current values MA, MB acquired from motor control sections 23 as described in the first embodiment or XY values calculated from magnetic bearing control amounts PID-IX, PID-IY acquired from magnetic bearing control sections 22 as described in the second embodiment may be the signals indicating the rotation states of the pump rotors 14. In the case of using either type of signals, each of the vacuum pumps 1A, 1B detects that an abnormality (i.e., excessive reactive product accumulation) has been caused at any of the vacuum pumps 1A, 1B.

An abnormality detection result detected at each of the vacuum pumps 1A, 1B is transmitted to a main control device 110 through a communication line 40. When the abnormality detection result is input from at least one of the vacuum pumps 1A, 1B, the main control device 110 displays a warning for notifying that the timing of maintenance of the vacuum pumps 1A, 1B comes.

(C6) In the present embodiment, the pump monitoring device 120 is provided in the controller 12 of the vacuum pump 1A as illustrated in FIG. 10, and the motor current value MB as the signal indicating the rotation state is input from the other vacuum pump 1B to a communication port 21 as a signal input section of the controller 12. Then, the pump monitoring device 120 compares the motor current value MA as the signal indicating the rotation state of the pump rotor 14 of the vacuum pump 1A and the motor current value MB input from the communication port 21, i.e., compares the magnitude ΔM| of the difference ΔM=MA−MB with a threshold α, thereby estimating the pump abnormality.

As described above, pump abnormality estimation is performed by each of the vacuum pumps 1A, 1B. Thus, redundancy in abnormality detection can be increased by use of both estimation results, and the abnormalities of the vacuum pumps 1A, 1B can be reliably detected.

Fourth Embodiment

FIG. 11 is a diagram for describing a fourth embodiment. In the fourth embodiment, a pump monitoring device 120 detects occurrence of an abnormality (i.e., excessive reactive product accumulation) for vacuum pumps attached to each process chamber of multiple semiconductor manufacturing devices. In an example illustrated in

FIG. 11, the pump monitoring device 120 monitors vacuum pumps 1A to 1F attached to process chambers 100A to 100C of three semiconductor manufacturing devices 10A, 10B, 10C.

A wireless communication device 140 is provided at each of the semiconductor manufacturing devices 10A to 10C. Moreover, a wireless communication device 200 is also provided at the pump monitoring device 120 so that information can be exchanged between each communication device 140 and the communication device 200. The pump monitoring device 120 can acquire, through the communication devices 140, 200, signals indicating rotation states of pump rotors of the vacuum pumps 1A to 1F from the semiconductor manufacturing devices 10A to 10C. Hereinafter, a case where the signal indicating the rotation state is a motor current value will be described by way of example.

Even in a case where three semiconductor manufacturing devices 10A to 10C are the same device, if the latest maintenance timing varies among the vacuum pumps 1A to 1F provided at the semiconductor manufacturing devices 10A to 10C, the next maintenance timing of the vacuum pump varies among the semiconductor manufacturing devices 10A to 10C. Thus, the pump monitoring device 120 performs vacuum pump abnormality detection for each of the semiconductor manufacturing devices 10A to 10C.

In the case of determining the abnormalities of the vacuum pumps 1A, 1B, the motor current values MA, MB of the vacuum pumps 1A, 1B are acquired from the semiconductor manufacturing device 10A. Abnormality detection processing based on the motor current values MA, MB is similar to the abnormality detection processing illustrated in FIG. 6 of the first embodiment. That is, an arithmetic section 210 sets a threshold α used for abnormality determination based on the motor current values MA, MB in an initial state. The threshold α is stored in a storage section 220. The arithmetic section 210 acquires the motor current values MA, MB from the semiconductor manufacturing device 10A at predetermined time intervals, and determines whether or not the magnitude |ΔM|=|MA−MB| of a difference between the motor current values MA, MB satisfies |ΔM|>α. Then, in the case of |ΔM|>α, it is determined that the abnormality has been caused at any of the vacuum pumps 1A, 1B, and a warning for prompting maintenance of the vacuum pumps 1A, 1B is displayed on a display section 230.

Regarding the vacuum pumps 1C, 1D, 1E, 1F of the semiconductor manufacturing devices 10B, 10C, abnormality determination processing similar to that in the case of the vacuum pumps 1A, 1B of the semiconductor manufacturing device 10A is performed separately for the semiconductor manufacturing devices 10B, 10C.

(C4) In the fourth embodiment, the pump monitoring device 120 includes the communication device 200 as an input section configured to receive the motor current values MA to MF from the vacuum pumps 1A to 1F provided at one or more semiconductor manufacturing devices 10A, 10B, 10C, and for each of the semiconductor manufacturing devices 10A, 10B, 10C, estimates that the abnormality has been caused at any of two vacuum pumps provided at each semiconductor manufacturing device.

With the pump monitoring device 120, the abnormalities of the vacuum pumps provided at the multiple semiconductor manufacturing devices 10A, 10B, 10C can be separately detected for the multiple semiconductor manufacturing devices 10A, 10B, 10C.

Note that in the example illustrated in FIG. 11, the communication device 200 employs a wireless method, but may employ a wired method. The wireless method is employed so that remote overall management can be easily performed.

Various embodiments have been described above, but the present invention is not limited to the contents of these embodiments. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. Moreover, multiple embodiments may be combined.

REFERENCE SIGNS LIST

1A, 1B, 1C, 1D, 1E, 1F . . . vacuum pump, 10 . . . semiconductor manufacturing device, 11 . . . pump main body, 12 . . . controller, 14 . . . pump rotor, 16 . . . motor, 17 . . . magnetic bearing, 17A, 17B . . . radial magnetic bearing, 17C . . . axial magnetic bearing, 21, 44 . . . communication port, 22 . . . magnetic bearing control section, 23 . . . motor control section, 100, 100A, 100B . . . process chamber, 110 . . . main control device, 120 . . . pump monitoring device, MA, MB . . . motor current value, SA, SB XY value, X1 a, X1 b, Y1 a, Y1 b, X2 a, X2 b, Y2 a, Y2 b, z . . . displacement sensor 

1. A pump monitoring device for detecting abnormalities of multiple vacuum pumps connected to an identical chamber, comprising: a calculation section that calculates a value corresponding to a comparison result of signals indicating rotation states of pump rotors of the multiple vacuum pumps included in the multiple vacuum pumps and that calculates a degree of scatter of a plurality of values each constituted of the value corresponding to the comparison result based on the signals acquired over time; and a determination section that sets a threshold value based on the degree of scatter and that estimates occurrence of the abnormality at any of the multiple vacuum pumps based on the comparison result.
 2. The pump monitoring device according to claim 1, wherein each signal indicating the rotation state is a motor current value of a motor configured to rotatably drive the pump rotor, and based on a difference between the different motor current values of the vacuum pumps, the determination section estimates that the abnormality has been caused at any of the multiple vacuum pumps.
 3. The pump monitoring device according to claim 1, wherein each pump rotor is magnetically levitated and supported by a magnetic bearing, and each signal indicating the rotation state is calculated based on a magnetic bearing control amount of the magnetic bearing.
 4. The pump monitoring device according to claim 1, further comprising: an input section configured to receive, from one or more vacuum processing devices including multiple vacuum pumps configured to perform vacuum pumping for chambers, signals indicating rotation states of the multiple vacuum pumps, wherein for each vacuum processing device, the determination section estimates that an abnormality has been caused at any of the multiple vacuum pumps.
 5. A vacuum processing device comprising: a chamber; multiple vacuum pumps configured to perform vacuum pumping for the chamber; and the pump monitoring device according to claim
 1. 6. A vacuum pump comprising: the pump monitoring device according to claim 1; a pump rotor to be rotatably driven by a motor; and an input section configured to receive signals indicating rotation states from other vacuum pumps, wherein the calculation section in the pump monitoring device compares a signal indicating a rotation state of the pump rotor and the signals input through the input section and indicating the rotation states and calculates the value corresponding to the comparison result; and the determination section in the pump monitoring device estimates a pump abnormality based on the value corresponding to the comparison result.
 7. The pump monitoring device according to claim 1, wherein the multiple vacuum pumps include a first vacuum pump and a second vacuum pump; and the value corresponding to the comparison result corresponds to a difference between the signals respectively representing the rotation states of the pump rotors respectively included in the first vacuum pump and the second vacuum pump.
 8. The pump monitoring device according to claim 1, wherein the degree of scatter corresponds to a standard deviation of the plurality of values. 